1. Field of the Invention
The present invention relates to a luminance signal. generating apparatus for use with a two-chip or 3-chip type video camera which obtains a color video signal by picking up an object by using a plurality of CCD (charge-coupled device) devices or the like, for example.
2. Description of the Prior Art
Heretofore, there have been widely used video cameras which derive a video signal by picking up an object by using one or a plurality of CCD devices regardless of consumer video cameras or professional video cameras.
In a video camera of 3-chip type (using three CCD devices), in particular, a light from an object is separated by a color separation prism into lights of red (R), green (G) and blue (B) components. The red, green and blue component lights thus obtained are respectively photoelectrically-converted into video signals (primary color signals) by three CCD devices, and a luminance signal and color difference signals R-Y and B-Y are obtained by effecting a variety of signal processings on the three video signals. Then, when these signals are output in the form of a composite or component video signal, there can be obtained a video signal whose reproducibility is higher than that of a video camera using one or two CCD devices.
A resolution of the 3-chip type video camera is the same as that of the video camera using one or two CCD devices. Therefore, in order to obtain a high resolution of a high definition television as expected in post-television, i.e., hi-vision, a resolution higher than a standard resolution of the NTSC system, the following two methods must be taken.
One method is to increase the number of pixels per unit area and the other method is to increase the area of CCD device with to thereby form the CCD device a number of pixels.
The above-mentioned method that increases the number of pixels per unit area needs an ultra-microlithography technology that is very difficult, and a yield is deteriorated considerably.
Further, according to the method in which the CCD device is formed with a number of pixels by increasing the area of the CCD device, a yield is deteriorated, and a power consumption is increased. Furthermore, when a video camera is designed so as to mount such large CCD devices, a resultant video camera becomes large in size and heavy, contrary to the goal that the video camera be miniaturized and reduced in weight.
In addition, in accordance with the increase of pixels by the above-mentioned two methods, a horizontal transfer efficiency is deteriorated, and the power consumption is increased with the increase of a transfer speed.